#include<stdio.h>
#include<unistd.h>

int g_val = 100;
int main()
{
    pid_t id = fork();
    if(id == 0)
    {
        //child
        int cnt = 0;
        while(1)
        {
            printf("I am child, pid: %d, ppid: %d, g+val: %d, &g_val: %p\n",getpid(),getppid(),g_val,&g_val);
            sleep(1);
            cnt++;
            if(cnt == 5)
            {
                g_val = 200;
                printf("child chage g_Val 100->200 success\n");
            }
        }
    }
    else
    {
        //father
        while(1)
        {

            printf("I am father, pid: %d, ppid: %d, g+val: %d, &g_val: %p\n",getpid(),getppid(),g_val,&g_val);
            sleep(1);
        }
    }
    return 0;
}
